There are important medical applications that will benefit from a desktop imaging tool which detects and maps parts per billion level metals and other heavy elements in tissues in vitro and in vivo. A compact instrument will be proposed for elemental imaging of dry tissues as well as living tissues based on monochromatic micro x-ray fluorescence (MMXRF). This tool, based on innovative, large-aperture, doubly-curved crystal optics, is capable of detecting ppb levels of transition metal and heavy elements with a spatial resolution of a few micrometers. This would assist in the research of Alzheimer?s and Parkinson?s diseases, prostate cancer and other medical issues. This can also be a relatively inexpensive tool for the screening and monitoring of environmental and occupational exposure of toxic elements. The Phase I research has been very successfully completed and the feasibility of the MMXRF has been clearly demonstrated. In this Phase II project, a prototype desktop MMXRF system will be developed that incorporates an interchangeable modular x-ray beam unit to probe samples with different x-ray energies. Spatial distribution of Mn, Fe, Se, and Cd will be mapped in tissues related to Alzheimer?s disease and prostate cancer using the prototype system. PROPOSED COMMERCIAL APPLICATIONS: Commercial applications will be seen in analytical labs and medical research centers in their investigation of the effects of toxic metals and other trace elements on biological functions. Simplified and inexpensive systems could have have applications for clinical screening of toxic element exposures and environmental monitoring. Other non-medical applications include materials science, forensics, the semiconductor industry and other industries where the sub ppm elemental imaging is desired.